Pulse-actuated circuit



Aug. 15, 1950 B. M. OLIVER PULSE-ACTUATED cmcurr 3 Sheets-Sheet 1 Filed Nov. 1, 1944 INVENTOR By B. M OLIVER My! J #4.

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1477' ORNE V Patented Aug. 15, 1950 UNITED PATENT oFncE; v 2,519,273 v m Bernard Ql ven. Ne ex N- assisn r W Be l Telep ne labe ifis;l worporatflb bl l nk PL a, gg'moration of New l t Application November 1, 1944, Serial No. 561,410 7 g eam (01, 259- 27) f e i This invention 'l'elateso to pulse actuated ein? cults and more ospeeifieally -pulseeeiuafaed eir cults for sweeping a beam a. cathodedi w ube- The main object of the. inMenbiQn isvtewnxo de an efficient and reliable nul e emfi lled circuit, the advantages ef we diseuee below. in its broader espeebs, ho ezvenibe veneer; is a pl ca eu ei e uhe fem oi wave generat eno- I v n pulse reflev tien WEB? image leeall e nde ie fia ce measurin systems. @eflerevsteme? f r examp e in the e stem d wl sed en e eh: cat on ef J, B.- l-l f-e e eared 9- 4R 32l rilfii A gust 1214996, whic i ue es fiteemxlfififi on fieptem e .121, 1948; mi e-h gh. m eue w earner w ves-modu ated euleesei very t me dura a e em tlz ,v .lfififififions tbe eef ll? eceived .fmm ebi els upon the emitted p lses im in e, and th r fle it on es v-fer- P311! u rebje iz m deter-m eel awm eee' e cation of phe distances t line ebie tsi nem the respective mime-lied ei ual a :reee

g1. Electrical variations received at me neeeimng p n nst tute a plurality of series or nam mpul s. Qh series c mp ng, Kim ey gzwnzl,e,v a ran d puls and ne or m m xefieeti ns e" ec o p es in erspe se w th. and :supnl me ted by variations due to noise etc, gfi-tep-depeetiw and mp ati n, the e.r e i empu ee. frequ n y l d the id e nalemign l are ex?- plied meme setofdefl t ng pl te e 1 rev oseille cope, to th therl te ela ese wlmb is ape ied a {swe p-e defleeting wave. lin tion of t e swe a s. etro ledhy slamm n :nul es pm th nan ml er we h ha e a :fi-Xe fime r l ion with m PfiQ $0 t e $0?- R s i g ran m d .pu e e and pmduce a s e o means e h of Whi h-41 fer a ,iper ed less than ;that :between pulses, l the in blue cat od -ra tu being set at! d "t e Mme tha i i ot being e bi example, the t ansm tted pul e :mayv new :a ee eliee e about 1 microsecond and be spaced by intervalsf appmx mate 2 m o epends t s timejne n t beeqns a tfl W l :tbe lim for wee ieee he b am in, iihe cat d -raytubfi may-be Q tbevnde of 50 to L00 m-icroaeconds. Ii-hue ,theiduty cyclei of the eweep wave (the {time --interva1 when the beam is being swept across me screen of ;th e cathode ray tube) .issaid "to be snort sime jghis ime infi wal is s a w l esp ct 1' the z me interval between {the transmitted pulses --;and hence between corresponding points in two successive-sweep cycles.

.It is .a "fu er obiee of "this inventipn .120 mevid a e eep eixeu bwb eb. i eetu ed by m hi h pme ees a wave each. l has a useful sweeping portion Whic g, Quee lien ccmeiderablv less; thee theeefle mile. th tween pulaeeend which is aecurete eesi; opexet n y I t is an th obieew this l ovpre ies a reliable .sweep c l puie sweep period and an a newb e am lified? on9. which m dems subem fielly lin ar .swe p,

I: e mine: object o t i ventin $9 .previes an efficient m 9 pulse-opened. wave ie ei eu t arxeneemena pr duees be eeee output voltages. e =..see. i e embo imen er the -iey me ma gee e o the ur n se. i lesi t ve d e/ 19w;

cirw c s u es a vSho Q i c cle 9 1- i e a? QB! QEQJ'JQII, e other w ea v u; a le :tq emwbae in an :arren eme l wh r in :tbe mean ng: we chrom-zin eulses are n t w esen v w ek? paced in mm? Th eemnr ses a vaeeum vtube "havin s mila in v 9 e hion i its out m ei ellit wi h e PQ' between me ex in e a; a meme; eet ide mamm l 9 $15 5: membe s 1: s ective y me the-anod n e thqde- A mten ial eeneect d ut eime l emf: er beween the eerm n le ef ehei define? member -we h ene exe le mm 512 934 e-aee cathode.- Qne in uctancemember edenser rennee e lee qss it ee m eels o e oth ies anl e member bee a eim' r den er ennec e e q e i an 1. 9 seu e seem re ationhe c w e lm l y 39m i5 9 0K perr Qdic fly y a negative -pulse peodu d b e mon vibra e i th e 1mm; orato in hieh we o .tbe lab is of n defin t u e en- .Beth eenelee en charged during the interval the tube is condye 118- f e we -l u-be i :eet 1 3 m inswce Ce 0; we indelen membex =?t 1 e r eel aw Q iuu tQ-fl -wi s h? Qh rfi s be wo eonde er-e a1le$1i eh? weep eousie ee' )4 9x m eas ns e d e her d c ea n e en; eouree s nonmetal one eee eu em flew ne t e ie th t be beeeel .nen eomlu ie ins.) an not in the when M e e vr elab ee er t m zinterve .ceneemnflne :13? o the mq ev b e er p lse, the m eier eh zge 1 1.5 lime; nd a one. eendenee dmzreesee t e erg-e t he ame ate @Wlh Qtber. 0er@ e& t eharee a lbalaneed :swe p ma efem be h ame The :reeuires i .e i hfi mduetam has e es u stebleal nced defleetmg wave ha in atiaz'r 3 coils can be decreased by providing mutual inductance between them. When the potential of the cathode (which is connected to vary its potential with change in output voltage) reaches a predetermined value, a diode connected between it and the monovibrator conducts and the monovibrator is reset and ready for another pulse. The bias on the diode can be varied to adjust the amplitude of the sweep. Varyingthe capacity of the two sweep condensers varies the sweep speed.

While the sweep circuit described above is suitable Ior use in radar systems, it will be readily apparent that it is in no way limited to use in such a system as it may be utilized in other systems or arrangements which require a sweep circuit which produces an output wave with a shorter deflectin period than the time interval between the synchronizing pulses used to control the initiation of the sweeping or deflecting periods. Moreover, the wave produced may be used for other purposes than to deflect an electronic beam.

The invention will be more readily understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

a Fig. 1 is a circuit diagram of a sweep circuit in accordance with the invention;

Figs. 2 and 3 are diagrammatical and graphical representations to aid in understanding the operation of the circuit of Fig. 1; and

Fig. 4 shows an oscillograph tube utilizing a circuit of this invention.

Referrin more particularly to the drawings, Fig. 1 shows, by way of example to illustrate the principles of this invention, a circuit for producing a recurrent sweep wave which may be used for deflecting the beam in a cathode-ray tube. The circuit also produces a pulse for unbianking" or brightening the beam in the tube while the beam is being deflected or swept across the screen. The circuit shown in this figure comprises four vacuum tubes VI, V2, V3 and V4 and their associated circuit connections. Input or synchronizing pulses of relatively short duration and of negative polarity are applied through the coupling condenser I!) to the cathode of the left half of the double diode VI, this cathode being connected to ground through the resistor II. If the pulses in the input circuit l2, which is hereby shown merely by way of example as a coaxial cable, are not of negative polarity, a phase inverter tube may be connected between the input circuit l2 and the tube VI. The anode of the left half of tube VI is connected to ground through the resistor 22 and through the coupling condenser I3 to the anode of the tube V3. It is also connected through the coupling condenser |4 to the first or control grid |5 of the tube V2. I

The tubes V2 and V3 are connected as a monovibrator acting in response to a pulse in the input circuit 2 to produce an output pulse of longer duration, as will be pointed out below. The tube V2 has its cathode connected to its third or suppressor grid and through a condenser It to ground, this condenser being shunted by resistor I1. The cathode of the tube V2 is also connected directly to the cathode of the tube V3. The grid I5 of the tube V2 is connected through a leak resistor l8 to the cathodes of the two tubes, while the first or control grid I! of the tube V3 is connected through the leak resistor to ground. The suppressor grid of the tube V3 is connected to its cathode while the second or screen grid 2| is connected to the positive terminal of a source 23 of about 300 volts, the negative terminal of the source 23 being connected to ground. While the source 23 has been shown as a battery, it is obvious that any other source suitably filtered to produce a steady voltage may be used instead. The screen or second grid 33 of the tube V2 is connected to the positive terminal of the source 23 through a resistor 24 and to the first grid I9 of the tube V3 through a small condenser 25 which has connected in parallel therewith the R-C circuit comprising a larger condenser 26 and a large resistance 21. Similarly, the small condenser I4 connected between the anode of the tube V3 and the first or control grid I5 of the tube V2 is shunted by the RC circuit comprising a larger condenser 28 and the resistance 29. The anode of the tube V2 is connected through the inductance 30, used for high-frequency equalizing purposes, and the resistor member 3| to the positive terminal of source 23, while the anode of the tube V3 is connected to the positive tenninal of the same source through the resistor 32.

The anode of the tube V3 is connected through the coupling condenser 40 to the grid of the triode V4. The grid oi. tube V4 is connected to ground through the resistor 4| and throu h the resistor 42 to the positive terminal of source 23. By this potentiometer arrangement, the grid of the tube V4 is placed at a positive potential. The anode of the tube V4 is connected through inductance member 43 to the positive terminal of the source 23, while the cathode thereof is connected through inductance member 45, equal to inductance member 43, and the resistor 46 to ground. A condenser 41 is connected between the cathode of the tube V4 and ground while a condenser 48 of like capacity is connected between the anode of the tube and ground. When the capacities of the condensers 41, 48 are changed, they are preferably changed by equal amounts. The cathode of tube V4 is connected through the coupling condenser 49 to the cathode of the right half of the tube VI, the anode of which is connected directly to the first or control grid IQ of the tube V3. The cathode of the right half of tube VI is connected through a resistor 50 to the variable tap 5| of a potentiometer 52, one end of which is connected to ground and the other end of which is connected through a resistor 53 to the positive terminal of the source 23. The output terminals 60 and GI of the sweep circuit are connected through the blocking condensers 63 and 64 to the anode and cathode, respectively, of the tube V4 while an unblanking or brightening output pulse is taken from the terminal 62 which is connected through blocking condenser 65 to the anode of the tube V2. These three terminals are connected to the cathode-ray tube 10 shown in Fig. 4.

The tube 10 includes an envelope enclosing an electron gun 12 including a control element 1|, two sets of deflecting plates 13 and 14, and a flourescent screen 15. The electron gun 12 comprises a cathode 16, the control element 1|, a first anode 11 and a second anode, including cylindrical member 18 and a conducting coating 19, for forming and accelerating a beam of electrons and for focussing it into a spot upon the fluorescent screen 15. The cathode 16 is heated by a filament which is supplied with current from a source of potential 8 The anode 11': is positively biasedlwifxh ncspectt thacathode 1&5: by means of: a source ot-dincct-..-poten3al; fir, while the anode members. is, 1-9: are positiyely biased with'respect tmthe anode 1:1? bYr means Q? the source. of direct potentiali .83; dig-nails are applied from the terminal: i'fizftathacqntnol ele: ment 1| in. order to, unblankl' the beam during substantially the time period; the active part \Qf the sweep wave is: being applied; from; the ten;-

minals. EB, 61- to the deflecting lates Th4; Al

other times: the beamis: blanked outgbe cause of the negative bias applied to the con-trill; element Hf by means of the source of direct potential: 8. connected: between the cathode 15 and the, con.- trol: element 1 1. A leak resistor 85; is also. com nectedinthis circuit; lie the other set-ofde ifi liting plates. 13 is applied: any suitable signals a visual representation of. which is toube vieuled on; the screen-.15.

The operation oi the circuit shown in 1 I;

potentialisalso transmitted lay-condenses 4%- to :1

the grid of the tubevlliand by condenser 14* to the control grid of: the tube-V2 As thacontrbl grid of thetube V2 is driven. negative, the screen grid and plate currents decreaseQand: the poten: tials of'these eleroents rise. As'the soiceenigrid 33: of: the tube Z2- rises in: potential abruptly, the coupling condenser carries; the control; grid of the tube V3 positive, asishownin. theportio'n Hit. of the wave shownain .1ine F"Of Eig2 2; and causes full. plate current to be drawn this tube. The full plate current in. tube Vin-drops the plate potential: below; thevaluecaused by the input pulse and the control grid of tubeV-Z is carried farther negative: completely cutting! oil, the latter. The potential of theiplate ofathesleft diode of the tube V! is; also. carried: below. that of the cathode ancl' this diode-stops conducting c rr s, hu disconnecting.- the pla e of-" tube vs from the input; circuitiand preventin any r io f ither-on theathen All ofz the abov ctions take pl ce. substanti lly fifitall' an cusly compared; with. he d ration tithe p lses ener ted by he. cir itior, i loth rwcrds, dur t time of. th leading edge; of all! the waves shown in lines A. to in Fig.2; During this time, as noted above, spacecuhrentis stopped in tube V2 and initiated; in. tube X63 andiasca result the screen grid'potentiala Ofl tube V12 has risen, suddenly and: the vplains potential: of. tube V3 has dropped suddenly;

The drop in the plate: potential of: tube V3.15 transmitted by the condenser 1A; tolthe control grid of tube V2 as a large negative step but since the time constantzof condenser- Mvand resistor It is very shortlthe control. grid-potential of tube V2 rises exponentially.- to. a value just below cut-oil completing the-spike H12 in he Wave shown at line C, Eig. 2-; They portion 1530f; the wave ofr'line C, Fig. 2', is also an exponential: curve but, with a compamatiuelyvvery lcn rn r od sicce ie t me constant at the ess rts; and: the es stors; hflihiifb It: s: is e y. larg or; r presented. this c sticsllsii remains nearly constant during the sweep and is below the cathode potential of tube V2 by an amount equal to the drop in plate potential of tube V2 multiplied by the ratio of the resistance of resiston Ill tothe sum. of oi resistor ll 82 and; oflnesistor 29.' a

' when. the screen. of tube V23 aces li uid-lin ng shown by the portion, lgiofrthciwaweifshowm at line E of Fig. 2, the coupling condenser 25 car-- tie the control r d oiatubev w a as already noted. Grid current in tube V3 then quickly charges condenser 25, but the control graig foi tube V3 is held positive by a flow of current from source 23 through resistpr 24, condenser 26, resistor 21 and resistor-20, this current producing; v a voltage drop across resistor which holdsitlm control grid positive with respect to ground. Thus the tubes, 312.: audits "quickly reach a temporarily stable state with tube V2 just out; oh and tube V3 conducting with its control gnid: being held only slightly; positive. Since cone denser I4 is discharged and condenser is, charged at this time, a small positiye voltage applied to the grid oj tube "or llne'ga't ive voltage applied'to the'glFiSLOifill is. circuit to revert to the initial stable 'st'atewhich existed before pheno /egg 91} the input pulse I00 shown at line'A of: Fig2a i Before the arrival of the input pulse, the grgdof the tube V4 is at a positive potential with respect to ground, as determined by resistors 4| and 42. The cathode of tube, V4 is slightly more positive than its grid -b'ecauseof the cathode current flowing through resistor 46. When the potential of the plate of tube V3 dnope suddenly (see the portion ID! ,of the-wave shown at line B, g. 2), tlieeounlinaccnsiens ra t control grid of tube V4 negative (see the portion I08 of the wave shown at line G, Fig. 2) and since the cathode of tube. 314. cannot drop as abruptly (because of condenser 41), tube V4 is. cut off. The current whioh wasflowing montthe positive B-supply through inductance 43, tube V4, inductance 45, and,- -r esistor 4fi to the grounded side of th battery is cutoff but a, charging current from the battery 23 now ligws into condenser 148 charging this c ondenscr -while at the same time the condenser 41 discharges through inductance 4'5 and resistanceil'fi. Ifithe inductance ofzthe'members. .43 and 45 were infinite the cur Refill: would: remain constantaouen-tho sweep time and condenser 48: wouldyhavccits charge-tamed invai positive direction andacondenser ttfw L d havecits charge varied? in. a negative direct on (either a decrease: of: aspositiv e charge or an in: crease; or a; negative "charge )1 at a constant-2 Thus the potential across C'z (condens-ezr'AI-if would rise and the potential across 01 (condqmer 41) would fall at a constant rate given by where e=voltage across the condenser Io=current through inductances 43 and 45 (and through V4, priorwto the arrival of the input pulse) A balancedoutput wayqthat one in which the derivatives with respect ttrtln'iof' th'volwt as ll lllllw the paternal. at

at the two terminals of the circuit are always equal in magnitude and of opposite sign, can normally be obtained by making C1=C2. It can be seen that with the inductance members infinitely large,

is constant, so that a linear sweep is obtained.

If the inductance of the coils 43 and 45 is not infinite, the sweep voltage across C2, for example, will be given very nearly by:

e.=I /g sin wt (2) where W so that J m/gcos wt and i cos wt (3) .If E,=fina1 value of sweep voltage required on each cathode ray tube plate t.=total sweep time o VT cos A Equation 7 gives the values of C1 and C: required to generate a sweep of amplitude E, in a time is having a linearity x. I0 is the current in tube V4. Equation 8 gives the minimum value of inductance required to achieve the linearity A. The inductance L is ordinarily computed for the worst case (that is, longest time, greatest voltage and least current) and is then left fixed at this value.

So that for nearly linear sweeps,

-L' C: E.

E i. 1 L= I0 10 If the two coils 43 and 45 are wound series aiding on a common core and tightly coupled, the inductance of each winding may be one half thatgiven by Equation 8 or 10.

The sweep velocity is ordinarily changed by varying C (see Equation 1). The sweep amplitude is limited to the potential to which the cathode of the second half of the double diode VI is held by the resistances 5|], 52 and 53. When during th sweep the cathode of the right half of the tube V! is driven negative by the sweep voltage, nothing happens until this cathode drops below its anode potential at which point the diode conducts and trips the sweep circuit back to normal by applying a sharp negative pulse III! to the grid of the tube V3 as shown in line F of Fig. 2, thus cutting oif the tube V3 and making its plate voltage swing in the positive direction, as represented by the portion I20 of the wave shown in Fig. 2, line B. For the duration of the sweep portions I09 and N0 of the waves shown in lines H and I of Fig. 2 (and in lines B and C of Fig. 3), the beam of the cathode-ray tube 10, to the deflecting plates 14 of which the sweep potentials are applied from the terminals and BI, is blanked ofi by the source 84. The beam is unblanked by the positive pulse I04 applied to the control member ll during the sweep time. This pulse is shown at line D of Fig. 2.

Circuit constants of an arrangement in accordance with this invention which has been actually constructed and satisfactorily operated have been indicated on the drawing. It is to be understood, however, that the invention is not limited to the use of elements having these particular constants.

Although the present invention has been described in terms of a preferred illustrative em bodiment, it should be realized that the invention and its several features are capable of being embodied in a wide variety of other forms and hence the invention is to be understood as comprehending such other forms as may fairly come within the spirit and letter of the claims. For example, the condensers C1 and C2 can be replaced by two terminal impedances of any suitable configuration. Moreover, the tube V4 can be replaced by an electromagnetic relay whose contacts are closed by the rise of anode potential in tube V3 and whose contacts open when this potential drops by any other suitable switching device.

What is claimed is:

1. The combination of a condenser with a source of direct potential for placing a charge thereon, an inductive element through which charging current for said condenser flows from said source, a second condenser having one terminal connected to a terminal of said first condenser for maintaining said terminals at substantially the same potential, means for maintaining said potential fixed in value, a current control element having its terminals connected respectively to a terminal of said first condenser and a terminal of said second condenser neither of which terminals is maintained at fixed potential, a second inductive element in a path having one terminal connected to said condenser terminals having a fixed potential so as to maintain said terminal of said path at said fixed potential, the other terminal of said path being connected to the terminal of said second condenser which is not maintained at a fixed potential, and means including a voltage pulse generator for alternately changing the conductivity of said current control element from a very low value to a relatively high value and from said high value to said low value, said means being under control of a varying potential dependent upon the potential of one of said condenser terminals the potential of which is not fixed.

2. The combination of claim 1 in which said current control element comprises a space current device having an anode, a cathode and a control element, and said last-mentioned means is connected to vary the potential of said control element with respect to said cathode.

3. In combination, a space current device having an anode, a cathode, and a control element, said anode and cathode being connected respectively to the terminals of a path including two similar inductances in series relation, a source of direct potential connected between the ends of the inductances remote from said anode and cathode, a shunt path between the anode and cathode of said space current device comprising two similar impedance members in series, means for maintaining a point in said shunt path between said impedance znembers at a reference potential, a conductive connection between said point in the shunt path and the path including said inductances at a point between said inductances, means connected to said control element to render said tube conducting in the absence of 10 input signals, and means for applying a negative pulse wave as an input signal to the control element of said space current device to render said tube non-conducting.

BERNARD M. OLIVER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,125,732 Bowman-Manifold et a1 Aug. 2, 1938 2,153,217 Van Der Mark Apr. 4, 1939 2,168,508 Barthelemy Aug. 8, 1939 2,178,464 Baldwin, Jr. Oct. 31, 1939 2,180,364 Norton Nov. 21, 1939 2,225,469 .Diebold Dec. 17, 1940 2,241,256 Gould May 6, 1941 2,250,202 Matusita July 22, 1941 2,265,290 Knick Dec. 9, 1941 2,354,668 Hallmark Apr. 4, 1944 2,363,810 Schrader et al. Nov. 28, 1944 2,414,486 Rieke Jan. 21, 1947 

